The present invention relates to a music box which plays pieces of music by picking reeds with a plurality of pins formed on a don In a conventional music box, a wind shaft and a base frame, to which a supporting portion of a driving gear and a comb are mounted, are mainly formed by molding iron and zinc via die casting. Also, Japanese Utility Model Publication No. S62-24310 and Japanese Laid-Out Patent No. H7-303079 provide a music box in which a base portion and a pair of parallel support arm portions, perpendicular to the base portion, are formed together as a base frame by means of bending a comparatively thick iron plate by pressing such that the support arm portions support a drum and a comb is fixed to the base portion. In this case, the comb comprises a plurality of combs or reeds assigned for given musical tones.
However, a base frame made of iron or zinc die cast requires a weight and volume more than given values in order to transmit vibration of the comb; also, a relatively long period of time is required for casting. Therefore, the cost for materials and manufacturing tend to be high. Furthermore, the weight of the base frame prevents improvement in productivity and causes an increased transportation cost. Also, the cost for row materials tends to be affected by the international market such that reduction in the cost of materials, such as zinc, would be limited. Therefore, it is difficult to reduce the cost for manufacturing and materials.
On the other hand, it is possible to reduce the weight and the manufacturing cost of the base frame which is formed by bending a plate. However, the rigidity and the weight of the base frame are not sufficient such that the quality of sound of the music box is deteriorated. If the thickness of the plate is increased in order to obtain the rigidity and the weight, on the other hand, it is difficult to press-process it. As a result, a larger presser is required and the life of a metal mold is shortened such that the cost for the processing equipment gradually increases.